Diaphragm and coil support



April 25, 1933. G. HOLST ET AL DIAPHRAGM AND COIL SUPPORT Filed Aug. 5. 1930 INVENTORS RICHARD SHEPHERD PIETER HENDNK ABRAHM VAN US BY muss HOLST 7 A O EY CIT Patented Apr. 25, 1933 UNITED STATES PATENT OFFICE GILLES HOLST, RICHARD SHEPHERD, AND PIETER HENDRIX ABRAHAM VAN LIS, OF EINDHOVEN, NETHERLANDS, ASSIGNORS TO RADIO CORPORATION OF AMERIGA,

A CORPORATION OF DELAWARE DIAPHRAGM AND COIL SUPPORT Application filed August 5, 1930, Serial No; 473,266, and. in the Netherlands September 3, 1929.

The invention relates to a body for supporting and centring the movable part of a device for converting electrical oscillations into acoustical vibrations or inversely such for example as loud-speakers, microphones, pick ups and the like.

One of the difficulties mostly encountered with such bodies is that at a determined sound frequency they show a strong resonance due to which the quality of the sound reproduction is injuriously aifected.

The invention has for its object to provide a supporting and centring body which has not the said disadvantage.-

According to the invention, the said body is made of a material which relative to its resonance phenomena is a so-called dead material. By a dead-material must hereinafter be understood a material whose natural frequency is not located in the frequency range reproduced by loud speakers. Such is the case, for example with pressed masses prepared with the aid, for example of artificial resins, pitch and the like. This afiords the advantage that the body in one operation can be pressed into the desired shape so that it is extremely suitable for be ing manufactured in series.

In one particular embodiment of the invention, in which said body serves to sup port and to centre the coil of an electro-dynamic loud speaker, it has a rhombic or in general a quadrangular shape, in which event in one of the diagonals is arranged the device for supporting the coil while in the other diagonal and on both sides of the said supporting device are provided the points for fixing the body to the magnet system.

In this case the device for supporting the coil may be constituted by a small cylinder on which the turns are provided and which is covered on one side by a conical part to the top of Which the vibrating member is secured.

In another embodiment of the invention,

the body has spiral extensions at the end of which are provided the points for fixing the body to the magnet system.

Preferably, at least two of the fixing points serve as connecting points for the Speech currents.

The electrical connection between the said connecting points and the coil may consist, for example of metal conductors pressed into the material of the body or be established by locally squirting the body with metal in a pulverized state according to the so called Schoop process. 7

The invention will be explained more fully with reference to the accompanying drawing which represents, by way of example, some embodiments of the invention. In the drawing Figure 1 is a plan view of an embodiment of the invention.

Figure 2 is a cross sectional view of the apparatus illustrated in Figure 1.

Figure 3 is a plan view of another mode of realization of the invention.

Referring to Figure 1, a rhombic body 1 of Bakelite serves to support and to centre the coil 2 representedin Figure 2, which is movably arranged in the magnetic field of an electro-dynamic loud speaker. In the diagonal 34 of this body is arranged the device for supporting the coil 2. Said device consists of a small cylinder 5 of F Bakelite which is secured to the diagonal and on which are arranged the turns of the coil. On one side said cylinder is covered by a conical part 6 to the top of which a vibrating member 7 is secured in the known manner. 1 For the sake of clearness the vibrating member is not represented in Figure 1.

In the diagonal 89 of the body and on either side of the cylinder 5 are provided points 10 and 11 for'fixing the body to the magnet system which is not represented. As distinctly appears from, Figure 1, these fixing points may also be easily used as con necting points for the conductors 12 and 13 whereby the speech current supplied at 10 and 11 to the body by the conductors 14 and 15 is transferred to the coil.

The body represented in Figure 3 has three spiral extensions 16 which at their ends are pierced with holes 17, 18 and 19 by means of which the body may be secured to the magnet system. The fixing points 17 and 18 also serve as connecting points for the speech currents supplied by means of conductors 20, 21 and 22, 23 to a coil 24 wound on a cylinder 25 which is secured to the body.

What we claim is:

1. A supporting member for the diaphragm of a moving coil type of loud speaker comprising a flat, pressed mass of Bakelite of dead beat material whose natural period of vibration is not within the range of normally audible frequencies, said flat, pressed mass being secured to the structure of said moving coil.

2. In combination a vibratile diaphragm, a conical shaped member secured to the apex of said diaphragm, a rod extending therefrom, a driving member secured to said rod, said driving member having a conical portion and a cylindrical portion, a driving coil on said cylindrical portion, a plurality of perforations in said conical portion, a flange at the junction of said conical portion with said cylindrical portion, a pair of extensions from said flange, means joined to said extensions forming a body portion, a second pair of extensions joined to said body portion, and means on said second pair of extensions for supporting said diaphragm from a suitable supporting member.

3. A body for centering and supporting the movable part of a device for converting electrical oscillations into acoustical vibrations or inversely, comprising a pressed mass prepared with the aid of an artificial resin whereby a dead beat member is obtained.

4. A body for centering and supporting the movable part of a device for converting electrical oscillations into acoustical vibrations or inversely, comprising a pressed mass of Bakelite whereby a dead beat member is obtained.

5. A body for centering and supporting the movable part of a device for converting electrical oscillations into acoustical vibrations or inversely, comprisin a mass prepared with the aid of an artificial resin and pressed into a fiat, quadrangularly shaped body provided with a plurality of diagonal members, means in one of said diagonals for connecting said body to said movable part, and means in other of said diagonals for supporting said body from a stationary part of said device.

6. A body for centering and supporting the movable part of a device for converting electrical oscillations into acoustical vibrations or inversely, comprising a body having the shape of a rhombic, members extending inwardly from said rhombic shaped body along the lines of the diagonals of said rhombic, means connected to the members extending along the shorter diagonal of said rhombic for connecting said body to the movable part of said device, and means connected to the members extending along the longer diagonal of said rhombic to support said body from a stationary part of said device, the members extending along the longer diagonal of said rhombic and the members forming the parallel sides of said rhombic being formed of a pressed mass of Bakelite whereby said body does not have a natural period of Vibration within the range of normally audible frequencies.

GILLES HOLST.

RICHARD SHEPHERD. PIETER HENDRIX ABRAHAM van LIS. 

